1. Field of the Invention
The present invention relates to a solid-state image pickup device and a method for manufacturing the same
2. Description of the Related Art
In recent years, as one of a solid-state image pickup device technology, such as CCD or CMOS image sensor, which raises the device performance, a backside-illuminated solid-state image device which raises sensitivity and advanced shading is reported. (see for example Back irradiation type CMOS image sensor BRIEF SUMMARY (ITE Technical Report Vol. 30, No. 25, PP. 25-28 IST 2006-14, CE 2006-43 (March 2006)))
By using an image sensor as a back-illuminated type, between a micro lens and a photo-conversion area, the optical obstacle is lost and high sensitivity and little optical shading are realized.
Moreover, since the flexibility of the interconnect layout by the side of the surface of an element increases, expensive miniaturization processing technology is avoidable. Furthermore, expansion of a dynamic range can also be enlarged because PN junction area increases.
By the way, irrespective of a back-illuminated type or a surface-illuminated type, when an electron which produced by photoelectric conversion is leakageed in an adjacent photo-conversion area, a crosstalk may be produced. Therefore, it is required to prepare an isolation area between image sensors. Moreover, in order to absorb light certainly especially in a back-illuminated type case, it is necessary to form the photo-conversion area in a deep area of a semiconductor layer for light of red with long wavelength. Generally, the isolation area is formed by high acceleration ion implantation so that the isolation area arrives at from the surface to the back side of the semiconductor layer. Moreover, a photo-conversion area is similarly formed in a deep area of the semiconductor layer by high acceleration ion implantation from a surface of the semiconductor layer.